Error while using the OnTrigger method and a RaycastHit.

Unity Engine
1

Hi folks, I have a problem and haven’t found a solution yet. I hope you can help me. I would like to add an item to my inventory by clicking on it in my 3D game. This should only work if the player is close to the item. This should be made possible by an OnTriggerEnter and OnTriggerExit method. The method checks whether an object that triggers with the player’s TriggerCollider has the tag “Selectable” and renames it “SelectableNP”. The OnTriggerExit method does the opposite. If I would click on the item then the selector script takes over. This checks whether the left mouse button was pressed and uses a raycast hit to determine whether I clicked on the collider of a game object with the “SelectableNP” tag. If so, it adds the GameObject to the inventory.

But the mistake comes in between: I can’t collect the item. Actually all three methods work because I have successfully tested them all. It seems to be because I can’t use both at once. At least I think so. But I’m not giving up and still hope that someone can find a solution.

Here are the OnTriggerEnter and OnTriggerExit methods:

private void OnTriggerEnter(Collider other)
        {
            if (other.gameObject.CompareTag("Selectable"))
            {
                other.gameObject.tag = "SelectableNP";
            }
        }

        private void OnTriggerExit(Collider other)
        {
            if (other.gameObject.CompareTag("SelectableNP"))
            {
                other.gameObject.tag = "Selectable";
            }
        }

And here is the update method of the selector script:

private void Update()
        {
            if (Input.GetMouseButtonDown(0))
            {
                Ray ray = Camera.main.ScreenPointToRay(Input.mousePosition);
                RaycastHit hit;

                if (Physics.Raycast(ray, out hit))
                {
                    if (hit.collider.gameObject.CompareTag("SelectableNP"))
                    {
                        IInventoryItem ItemToCollect = hit.collider.GetComponentInParent<IInventoryItem>();

                        inventory.AddItem(ItemToCollect);
                    }
                }
            }
        }
2

There is a much more straightforward (and probably more reliable) way to achieve what you’re doing ;):

void OnClick()
{
    RaycastHit hit;
    Ray ray = camera.ScreenPointToRay(Input.mousePosition);
    
    if (Physics.Raycast(ray, out hit))
    {
        if(hit.transform.gameObject.tag == "Selectable" && Vector3.Distance(hit.transform.position, player.transform.position) < 2f)
        {
            // pickup/interact etc
        }
    }
}

No need for colliders etc

3

Oh. Thats it? Thank you!

But I would still like to know why my problem is there.

4

Could be a number of things, it’s hard to tell. The code seems fine. Maybe the colliders aren’t triggering like you’re expecting. Maybe AddItem isn’t doing what you’re expecting. Maybe GetComponent is failing. If you sprinkle some Debug.Logs in there you should be able to figure it out :slight_smile:

5

Ah yes, works every time. Source: haven’t seen it fail yet! :slight_smile:

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